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Electrical power lines can, under certain circumstances, carry more than double the amount of electrical energy than their current ‘static’ rating suggests, a collaborative industrial study has shown.
The research project, led by energy specialist Parsons Brinckerhoff, has analysed the ‘cooling’ effect of wind on the rating of electrical power lines.
The study has major implications for the wind power industry and particularly windfarms in remote rural locations, where the existing electrical infrastructure is often the limiting factor to the capacity of generation that can be economically connected.
To undertake the 42-month programme, Parsons led a research consortium of Alstom Grid, Durham University, Imass and ScottishPower Energy Networks. The consortium was funded by the UK government under the Technology Strategy Board programme.
The aim of the study was to develop an approach to help reduce capacity restrictions placed on electricity networks, which can affect connection costs and schedules. The focus was on power systems between 33kV and 132kV. In order to prove the concept, a ‘control system’ was developed and prototyped, which had at its heart a series of software programs developed by Durham University and Imass to model the thermal state of the power system.
To test the system, a section of ScottishPower’s 132kV network in North Wales was chosen for field trials. Since January 2010, electrical, thermal and meteorological data from the trial has been collected by Alstom Grid and processed using the developed thermal state estimation and generator control system software.
Calculations covered realtime ratings of overhead lines, electric cables and power transformers. The results showed that an enhanced knowledge of the thermal state of network components could enhance power flow capabilities. Key findings revealed a potential capacity increase during periods of peak windfarm generation of up to 150% for overhead lines, up to 6% for electric cables and up to 10% for power transformers.
Following the initial trial, ScottishPower will now further develop the technology to enable the connection of more renewable generation without the need to invest in network infrastructure. A new consortium between Parsons Brinckerhoff, ScottishPower and a number of Smart Grids equipment suppliers has been formed to drive the technology forward, supported by Ofgem’s Low-Carbon Networks (LCN) funding initiative.
The objective is to implement a realtime thermal rating system across a wide area to give ScottishPower improved visibility of the ‘actual’ thermal operating status of its network. It will involve the installation of weather stations at numerous sites across North Wales and a centralised network management system, along with overhead line temperature monitoring systems for validation purposes.
Parsons Brinckerhoff said its role would be to deliver the project by recruiting project partners, planning the scope of work and project programme, and by redesigning the system architecture to allow for operation across large geographical areas and to allow for a control room interface. The company will also assist with the application for LCN funding and the provision of day-to-day project management services, support for software development, and technical support such as data analysis and commissioning tools.
This phase of the project is planned to run from 2010 to 2013.